As generally recognized, the centrifugal compressor compresses gas utilizing the centrifugal force generated when the gas passes through rotating impeller in the radial direction. The centrifugal compressor is used in plants for petrochemistry, natural gas, or air separation.
As the centrifugal compressor, the one shaft multistage centrifugal compressor and the integrally geared centrifugal compressor (hereinafter, referred as “a geared compressor”) are known. In the one shaft multistage centrifugal compressor, the impeller compressing the gas is attached to a single shaft. In the geared compressor, the impeller is attached to ends of pinion shafts. As a variation of the geared compressor, the geared compressor, in which the working fluid is compressed by multiple compressor sections with impellers provided to the ends of multiple driven pinion shafts, is known (see Patent Literature 1, for example).
FIG. 5 is a schematic cross-sectional plain view of a conventional geared compressor 101. As shown in FIG. 5, the conventional geared compressor 101 includes: the driving source 19; the drive shaft 2 rotatably driven by the driving source 19; the speed increasing gear system 110 to which the driving force of the drive shaft 2 is transmitted; the no. 1 driven pinion shaft 5 protruding to both sides of the no. 1 driven pinion gear 112 constituting the speed increasing gear system 110; and the no. 2 driven pinion shaft 6 protruding to both sides of the no. 2 driven pinion gear 113 constituting the speed increasing gear system 110. In the conventional geared compressor 101, each of the first stage compressor section 107 and the second stage compressor section 108, is provided to each end of the no. 1 driven pinion shaft 5. Also, the third stage compressor section 109 and the counter weight 116 are provided to one end and the other end of the no. 2 driven pinion shaft, respectively.
The speed increasing gear system 110 includes: the drive gear 111 provided to the drive shaft 2; the no. 1 driven pinion gear 112 provided to the no. 1 driven pinion shaft 5; and the no. 2 driven pinion gear 113 provided to the no. 2 driven pinion shaft 6. Having the gears configured as described above, rotation of the drive shaft 2 is accelerated and transmitted to the driven pinion shafts 5, 6.
The first stage compressor section 107 and the second stage compressor section 108 are connected each other through the first stage heat exchanger 27. The second stage compressor section 108 and the third stage compressor section 109 are connected each other through the second stage heat exchanger 28.
Configured as described above, the work fluid introduced to the geared compressor 101 is compressed by the three-staged compressor sections 107, 108, 109. In addition, compression efficiency is improved by intermediate cooling of the work fluid by the heat exchangers 27, 28 provided between the compressor sections.